// 📦 IndexedDB Helper
/** @type {()=>Promise<IDBDatabase>} */
function openDB() {
  return new Promise((resolve, reject) => {
    const request = indexedDB.open('directory-handle-db', 1);
    request.onupgradeneeded = () => {
      request.result.createObjectStore('handles');
    };
    request.onsuccess = () => resolve(request.result);
    request.onerror = () => reject(request.error);
  });
}

// 💾 Store a directory handle
/** @type {(handle:FileSystemDirectoryHandle)=>Promise<void>} */
export async function setDirectoryHandle(handle) {
  const db = await openDB();
  const tx = db.transaction('handles', 'readwrite');
  tx.objectStore('handles').put(handle, 'user-folder');
  await tx.done;
}

// 📂 Retrieve a directory handle
/** @type {()=>Promise<FileSystemDirectoryHandle|false>} */
export async function getDirectoryHandle() {
  const db = await openDB();
  const tx = db.transaction('handles', 'readonly');
  return new Promise((resolve, reject) => {
    const getRequest = tx.objectStore('handles').get('user-folder');
    getRequest.onsuccess = () => resolve(getRequest.result);
    getRequest.onerror = () => {
      console.error('Error retrieving directory handle:', getRequest.error);
      return resolve(false);
    }
  });
}

/** @type {(handle:FileSystemDirectoryHandle, parts:string[])=>Promise<File|false>} */
export async function drilldown(handle, parts)
{
  try
  {
    let filePointer = handle;
    for(let i=0; i<parts.length-1; i++)
    {
      filePointer = await filePointer.getDirectoryHandle(parts[i], {create: false});
    }
    const leaf = await filePointer.getFileHandle(parts[parts.length-1], {create: false});
    return await leaf.getFile();    
  }
  catch(e)
  {
    return false
  }
}

// // 🔐 Check or request permission
// async function verifyPermission(handle, mode = 'readwrite') {
//   const opts = { mode };
//   if ((await handle.queryPermission(opts)) === 'granted') return true;
//   if ((await handle.requestPermission(opts)) === 'granted') return true;
//   return false;
// }
// 
// 
// // 📌 Request persistent storage
// async function ensurePersistentStorage() {
//   if (navigator.storage && navigator.storage.persist) {
//     const granted = await navigator.storage.persist();
//     console.log(granted
//       ? '✅ Persistent storage granted.'
//       : '⚠️ Storage may be cleared under pressure.');
//   }
// }